Two-component polyurethanes

Abstract

Two-component polyurethanes without inclusion of gas are described, whose hydroxylated component contains a zeolitic dehydrating agent which corresponds to the following formula in its anhydrous form: ##EQU1##

We claim: 
     
       1. A method for preparing polyurethanes free of gas inclusions by mixing a component containing a hydroxylated reagent and a component containing the polyisocyanate reagent which can be stored separately without any major change in reactivity, characterized in that the component containing the hydroxylated reagent contains a dehydrating agent formed by a zeolite having the general formula in its anhydrous form:   aNa.sub.2 O.bK.sub.2 O.cMO.Al.sub.2 O.sub.3.mSiO.sub.2     in which   b is a number between 0.1 and 0.5, and   c is a number between 0.1 and 0.5, in which     a is a number such that   a+b+c=1;     in which     m is a number between 1.35 and 2.35, in which     M is calcium or magnesium.   
     
     
       2. A method for preparing polyurethanes in accordance with claim 1, characterized in that in its anhydrous form, the zeolitic dehydrating agent corresponds to the following formula:   aNa.sub.2 o.bK.sub.2 O.cCaO.Al.sub.2 O.sub.3.mSiO.sub.2     in which   b is a number between 0.20 and 0.40, and   c is a number between 0.15 and 0.45, in which     a is a number such that   a+b+c=1,     in which     m is a number between 1.35 and 2.35.   
     
     
       3. A method for preparing polyurethanes in accordance with claim 1 or 2, characterized in that the zeolitic dehydrating agent accounts for 2 wt.% to 20 wt.% of the hydroxylated component. 
     
     
       4. A storage-stable component for preparing polyurethanes without gas inclusions, consisting of at least on polyhydroxylated organic reagent, and a dehydrating agent characterized in that in its anhydrous form, the dehydrating agent is a zeolite having the following general formula:   aNa.sub.2 O.bK.sub.2 O.cMO.Al.sub.2 O.sub.3.mSiO.sub.2     in which   b is a number between 0.1 and 0.5, and   c is a number between 0.1 and 0.5, in which     a is a number such that   a+b+c=1;     in which     m a number between 1.35 and 2.35, and in which   M is calcium or magnesium.   
     
     
       5. A component for polyurethane in accordance with claim 4, characterized in that the dehydrating agent is a zeolite corresponding, in its anhydrous form, to the following formula   aNa.sub.2 O.bK.sub.2 O.cCaO.Al.sub.2 O.sub.3.mSiO.sub.2,     in which   b is a number between 0.20 and 0.40,   c is a number between 0.15 and 0.45, in which   a is a number such that   a+b+c=1;     and     in which m is a number between 1.35 and 2.35.   
     
     
       6. A component for polyurethane in accordance with claim 4 or 5, characterized in that the zeolite dehydrating agent accounts for 2 wt.% to 20 wt.% of the component.